They've already built one. Seems to work fine.
YouTube - Verticopter Prototype
This seems to be a 1:5 scale variant.
Disk loading may be high, but wouldn't the pay-off be worth it?
X-Plane is a relatively precise sim. If one designs any plane according to its blueprint specs, the attained flight data is amazingly accurate. Unlike other "toy" sims like MSFS, which require designs to have data punched in for flight behavior AND looks, X-Plane derives flight behavior FROM design. Numerous prototypes have been tested in X-Plane first. Of course, X-Plane designs allow you to enter unrealistic figures, that could not be attained in real life, such as over-the-top power-to-weight ratios, but given realistic input, realistic flight models can be expected.
"No people allowed in the vicinity" seems like a valid rule... but the blast of any aircraft is a force to be reckoned with. This design seems to actually shield bystanders from the dangerous props.
My $0.02